Bug: If your computer or connection lags too much on co-op mode, sometimes you will lose connection and be removed from the game back to the menu. Sometimes though, when the connection is lost, the screen just turns black with the spinning Pentagram at the bottom as a loading screen, but it just stays there. You are stuck. You have to close the game down and restart it.

Revealing mistake: If you get a slow motion bullet cam shot on a zombie wearing a helmet or hat, and it's a head shot, you can see the hat fly off when the bullet hits, but often you will see the layers of the hat pass through the zombie's head with no collision.

Bug: Labyrinth of Death: In the rafter like area after the beginning spawn zone, on the right side of it on the top level, there is an explodable propane tank there. Sometimes when viewing it, it will be partly stuck in the ground as if it sank through the metal.

Trivia: Labyrinth of Death: After the first safe room, you have to go and hit the control to manually open a large door. It takes the door a few seconds to finally start opening. There is a horde of zombies on the other side waiting. Once it opens, if you are zoomed in with binoculars, your sniper scope, or happen to be right next to the door, you can see the zombie in the middle at the front is standing there saluting for a moment, and then snaps out of it and starts coming after the players with the rest of the horde.